It is known to utilize filaments in the reinforcement of gas turbine engine components such as compressor and turbine blades and vanes (hereinafter referred to as "blade(s)"). In particular, the potential for usage of high modulus, high strength fibers, such as carbon, silicon carbide, boron and others in a resin or metal matrix is widely recognized.
One of the problems in using filamentary reinforcements in gas turbine engine blades resides in providing suitable means for mounting them on a ring, hub, disk or other support in the compressor or turbine section of the engine. Typically, a blade requires an enlarged base (referred to as the root) formed to a shape (e.g., typically a dovetail shape) adapted for mounting on the ring, hub, disk or other support in the compressor turbine section. Typically, the root is inserted in a dovetail slot in the ring, hub, disk or other support and may be pinned thereto by an attachment pin inserted through the blade root.
There is a need to provide a 3D fiber preform reinforced composite blade having a root with a desired enlarged, divergent shape, such as a dovetail shape, for insertion in a complementary slot in the ring, hub, side or other support.
The Warken U.S. Pat. No. 2,995,777 issued Aug. 15, 1961, discloses the formation of a dovetail configuration in a blade root by laying up impregnated cloth or rovings about a shank member.
The Wilder U.S. Pat. No. 3,132,841 issued May 12, 1964; the Stargardter U.S. Pat. No. 3,679,324 issued July 25, 1972 and the Stone U.S. Pat. No. 3,731,360 issued May 8, 1973, illustrate the forming of a dovetail configuration of a blade by the use of wedges inserted into the end of a laminated preform.
Three-dimensional (3D) braiding is a known process for forming fiber preforms by continuous intertwining of fibers. During the 3D braiding process, a plurality of fiber carriers in a matrix array are moved simultaneously across a carrier surface. A fiber extends from each carrier member and is intertwined with fibers from other carrier members as they are simultaneously moved. The fibers are gathered above the carrier surface by suitable means. The 3D braiding process is characterized by an absence of planes of delamination in the preform and results in a tough, crack growth resistant composite article when the preform is impregnated with resin (such as epoxy), metal or other known matrix materials. The Bluck U.S. Pat. No. 3,426,804 issued Feb. 11, 1969, and the Florentine U.S. Pat. No. 4,312,761 issued Jan. 26, 1982, illustrate machines for braiding a 3D article preform using fiber carriers in a rectangular, row-column matrix or circular, concentric-ring matrix.
It is an object of the invention to provide a process for making a 3D braided fiber preform reinforced gas turbine engine blade having an airfoil and an integral root having an enlarged, divergent shape for securing to a ring, hub, disk or other support in the compressor or turbine section of a gas turbine engine